I experience a problem with ISR 1800 series routers.
We installed on the 2 sites of a customer 2 ISR 1800 routers to Internet through ADSL. One on a PSTN line and one on ISDN line.
On the first site users has no problem to connect to remote server with RDP on a specific port - 3819. On the other site they can not. The configurations are strictly similar. A GRE and IPSec tunnel connect both sites together. There is no communication problem between both sites. We installed successfully VoIP PBX on one site and remote phones on the other site.
Do somebody has an idea ? We already checked the MTU size but without any success.
Thanks in advance.